[1,2,4]Triazolo[1,5-a]pyrimidin-2-amine, 5,7-dimethoxy-

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The key study for skin sensitisation was conducted in accordance with the following guidelines:

- OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

- EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

- EPA OPPTS 870.2600 (Skin Sensitisation)

The study was conducted in line with GLP. A reliability rating of 1 according to the criteria of Klimisch, 1997.

Migrated from Short description of key information:
The Local Lymph Node Assay (LLNA) was conducted to assess the potential of ADTP to cause contact sensitization by measuring the lymphocyte proliferative responses from auricular lymph nodes following topical application of the test material to the mouse ear.

Screening Study: Three daily topical applications of 1%, 5%, 15%, 30%, or 60% ADTP were given to one animal at each dose level. Erythema was absent in the mice treated with 1%, 5%, and 15% ADTP, while the mice dosed with 30% and 60% ADTP demonstrated slight erythema on days 2 and 3, that resolved by day 6. Body weights were unaffected in all dose groups. Results from this study were used to determine the dosing concentrations for ADTP in the LLNA.

LLNA: Six female mice/group received 5%, 20% or 60% ADTP, or vehicle (propylene glycol (PG)), on days 1-3. On day 6, uptake of 3H-thymidine into the auricular lymph nodes draining the site of chemical application was measured five hours post administration. Proper conduct of the LLNA was confirmed via a positive response using 30% a-hexylcinnamaldehyde (RCA), a moderate contact sensitizer, which elicited proliferation that was 12.1% in comparison to vehicle-treated mice.

Erythema was absent in the mice treated with 5% and 20% ADTP, while the mice dosed with 60% demonstrated slight erythema on days 2 and 3 that resolved by day 6. Body weights were unaffected in all dose groups.
ADTP elicited proliferative responses with stimulation indices (SI) that were respectively 1.2, 1.3 and 1.2 in comparison to the vehicle-treated mice. ADTP did not demonstrate dermal sensitization potential in the mouse LLNA as the lymph nodes draining the area of topical application did not demonstrate a 3-fold proliferation when compared to vehicle-treated mice.

Justification for classification or non-classification

The substance is classified as 'not sensitising' according to the criteria set out in Directive 67/548/EEC (DSD) and also Regulation (EC) No. 1272/2008 (CLP).